Gas heat pump air conditioning system

ABSTRACT

A gas heat pump air conditioning system includes: a gas engine that generates power by using gas as a fuel; a heat pump cycle including a compressor that is driven by the gas engine and at least one heat exchanger disposed in an interior space and air-conditioning the interior space by the heat exchanger; a power generator that is driven by the gas engine and generates electric power; and a local air conditioner that is disposed in the interior space in which the heat exchanger is disposed and that air-conditions the interior space by using the electric power generated by the power genera or.

BACKGROUND

1. Technical Field

The present disclosure relates to gas heat pump air conditioningsystems.

2. Description of the Related Art

In a typical gas heat pump air conditioning system, a compressor isdriven by a gas engine. When the air conditioning load is low, however,the gas engine rotates at low speed, and the efficiency of the systemdecreases. In view of this, it is proposed to change the driver of thecompressor from the gas engine to a motor (see Japanese UnexaminedPatent Application Publication No. 2011-7356). It is also proposed toswitch a driving force necessary for the compressor between the gasengine and the motor in accordance with an air conditioning load, or touse both the gas engine and the motor (see Japanese Patent No. 4958448).

FIG. 9 illustrates a configuration of a typical gas heat pump airconditioning system described in Japanese Unexamined Patent ApplicationPublication No, 2011-7356 and Japanese Patent No. 4958448. A heat pumpcycle is constituted by an indoor unit 115 a, an indoor unit 115 b, anexpansion valve 114, a heat exchanger 113, refrigerant pipes 116, and acompressor 112. The compressor 112 is driven by a gas engine 111 througha pulley 130, a pulley 131, and a belt 132. Adjustment of a clutch 133enables a power generator 120 to be driven by the gas engine 111 througha pulley 134, a pulley 135, and a belt 136.

In Japanese Unexamined Patent Application Publication No. 2011-7356,electric power generated by a power generator 120 is stored in a storagebattery 125. When the air conditioning load is high, a large amount ofheating energy or cooling energy is required for the indoor unit 115 aand the indoor unit 115 b. Thus, the compressor 112 needs to be operatedat high rotation speed. That is, the gas engine 111 is operated at highrotation speed. Electric power generated by the power generator 120 isstored in the storage battery 125. On the other hand, when the airconditioning load is low, a small amount of heating energy or coolingenergy is required for the indoor unit 115 a and the indoor unit 115 b.Thus, the compressor 112 needs to be operated at low rotation speed.However, operation of the gas engine 111 at low rotation speed causes alow efficiency. Thus, the control circuit 126 performs control such thatthe compressor 112 is driven by the power generator 120. That is, thepower generator 120 is driven as a motor by using electric power of thestorage battery 125, and rotates the compressor 112 through the clutch137, the pulley 138, the pulley 139, and the belt 140.

In Japanese Parent No. 4958448, electric power for driving the powergenerator 120 as a motor is supplied from a commercial power supply 123through a panel board 122 and an inverter 121. The control circuit 126performs control so as to minimize the sum of a running cost in drivingthe compressor 112 by the gas engine 111 and a running cost in drivingthe compressor 112 by the power generator 120 (a motor).

SUMMARY

The techniques described in Japanese Unexamined Patent ApplicationPublication No. 2011-7356 and Japanese Patent No. 4958448 are notexpected to increase the efficiency with a high load.

One non-limiting and exemplary embodiment provides a technique forincreasing the efficiency of a gas heat pump air conditioning systemwhile maintaining comfort of a room.

In one general aspect, the techniques disclosed here feature a gas heatpump air conditioning system including: a gas engine that drives acompressor by using gas as a fuel; a heat pump cycle including thecompressor that is driven by the gas engine and at least one heatexchanger disposed in an interior space, the heat pump cycleair-conditioning the interior space by the heat exchanger; a powergenerator that is driven by the gas engine and generates electric power;a local air conditioner that is disposed in the interior space in whichthe heat exchanger is disposed and that air-conditions the interiorspace by using the electric power generated by the power generator; anda control circuit that controls the power generator and the heatexchanger in accordance with an air conditioning load of the interiorspace.

The technique described above can increase the efficiency of the gasheat pump air conditioning system while maintaining comfort in a room.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a gas hear pump air conditioning system according toa first embodiment of the present disclosure;

FIG. 2 is a view of a gas heat pump air conditioning system according toa second embodiment of the present disclosure;

FIG. 3 is a graph showing efficiency characteristics of a gas heat pumpcycle;

FIG. 4 is a graph showing a relationship between the clutch level andthe number of revolutions of a power generator;

FIG. 5 is a graph showing a relationship between the number ofrevolutions of the power generator and the volume of gas consumed by agas engine;

FIG. 6 is a graph showing a relationship between the number ofrevolutions of the power generator and a generation amount;

FIG. 7 is a flowchart showing control by a control circuit;

FIG. 8 is a flowchart showing control by the control circuit;

FIG. 9 is a view of a typical gas heat pump air conditioning system; and

FIG. 10 is a view for explaining problems of the typical gas heat pumpair conditioning system.

DETAILED DESCRIPTION Underlying Knowledge Forming Basis of the PresentDisclosure

In a typical gas heat pump air conditioning system illustrated in FIG.9, indoor units 115 a and 115 b are disposed on a ceiling. Thus, in acase where a room has both an area requiring air conditioning and anarea not requiring air conditioning, it is not easy to perform airconditioning of these areas selectively. Consequently, air-conditioningenergy (gas) is wasted.

A case where an air conditioning load is high and a case where an airconditioning load is low will now be described. In air conditioning aninterior space, an intended temperature (a target temperature) is setfor an area to be air-conditioned (an air-conditioned area). The airconditioning system is controlled such that the air-conditioned areareaches the intended temperature. An example of a high load is the timewhen the air conditioning system starts with a large difference betweenthe current temperature and the intended temperature in theair-conditioned area and with the necessity of a high degree of heatingenergy or cooling energy for an indoor unit. Once the air conditioningsystem starts and continues its operation, the difference between thecurrent temperature and the intended temperature in the air-conditionedarea gradually decreases, and the degree of heating energy or coolingenergy necessary for the indoor unit also decreases. That is, theair-conditioned area comes to be under a low load (a so-called steadystate or part load conditions).

As illustrated in FIG. 10, suppose an interior space is generallydivided into an ordinary-air-conditioned area 160, alocally-air-conditioned area 161, and an air-conditioning-free area 162.The ordinary-air-conditioned area 160 is an air-conditioned area with anordinary air conditioning load. The locally-air-conditioned area 161 isan air-conditioned area with a high air conditioning load. Theair-conditioned-free area 162 is an area above thelocally-air-conditioned area 161. Suppose a generally heavily clothedresident 170 works in an upright position in the air-conditioned area160. Suppose a generally lightly clothed resident 171 works while beingsitting in the locally-air-conditioned area 161. Since the resident 171works while being sitting in the locally-air-conditioned area 161, thespace above the locally-air-conditioned area 161 does not directlyaffect warmth or coldness felt by the resident 171. That is, theair-conditioning-free area 162 is originally a useless area for airconditioning.

In view of a comfort index predicted mean vote (PMV), the temperaturenecessary for obtaining comfort is determined on the basis of the stateof clothes of a resident and working conditions. In the case of aheating operation, for example, the temperature required in thelocally-air-conditioned area 161 is higher than that required in theordinary-air-conditioned area 160. That is, in the example illustratedin FIG. 10, the air conditioning load of the locally-air-conditionedarea 161 is higher than that of the ordinary-air-conditioned area 160.In addition, the locally-air-conditioned area 161 and theair-conditioning-free area 162 need to be air-conditioned by the indoorunit 115 b. Thus, the locally-air-conditioned area 161 is generallyunder an extremely high load, as compared to theordinary-air-conditioned area 160. Although the locally-air-conditionedarea 161 is under a high air conditioning load, thelocally-air-conditioned area 161 might be insufficiently air-conditionedbecause of, for example, difficulty in airflow from the indoor unit 115b. In this case, comfort satisfactory for the resident cannot beobtained. As the degree of heating energy or cooling energy suppliedfrom the indoor unit 115 b increases, unnecessary heating energy orcooling energy supplied to the air-conditioning-free area 162 increases,resulting in an increase in waste of air-conditioning energy (gas).

A gas heat pump air conditioning system according to a first aspect ofthe present disclosure includes: a gas engine that drives a compressorby using gas as a fuel; a heat pump cycle including the compressor thatis driven by the gas engine and at least one heat exchanger disposed inan interior space, the heat pump cycle air-conditioning the interiorspace by the heat exchanger; a power generator that is driven by the gasengine and generates electric power; a local air conditioner that isdisposed in the interior space in which the heat exchanger is disposedand that air-conditions the interior space by using the electric powergenerated by the power generator; and a control circuit that controlsthe power generator and the heat exchanger in accordance with an airconditioning load of the interior space. In other word, the controlcircuit includes a processor and a memory storing a program, theprogram, when being executed by the processor, causing the controlcircuit to perform operation including controlling the power generatorand the heat exchanger in accordance with an air conditioning load ofthe interior space.

In the first aspect, the local air conditioner locally air-conditionsthe interior space by using electric power generated by the powergenerator. The power generator and the indoor unit are controlled inaccordance with the air conditioning load of the interior space. The useof the local air conditioner in the air-conditioned area with a highload can reduce the load of the compressor constituting the heat pumpcycle. Thus, the efficiency of the gas heat pump air conditioning systemin the case of a high load can be increased.

The local air conditioner is preferably an air conditioner that does notneed to be fixed to the ceiling unlike an indoor unit that is fixed tothe ceiling because of restriction concerning refrigerant pipes. Thelocal air conditioner can be disposed in an air-conditioned area with ahigh load. The local air conditioner can be disposed near a resident inan air-conditioned area with a high load, for example. In this case,heating energy or cooling energy is not easily supplied from the localair conditioner to an area that does not need air conditioning, andthus, waste of air-conditioning energy (gas) can be reduced. In a casewhere the local air conditioner is disposed near the resident, comfortof the resident is not easily impaired.

Examples of the local air conditioner include a warm-air fan heater thatis operated with electricity in a heating operation. Specifically, thewarm-air fan heater is disposed near the feet of the resident and isoperated with electric power generated by the power generator. In thismanner, even when the indoor unit stops, comfort of the resident can bemaintained. In a heating operation by the indoor unit, an area that islocated between the indoor unit and the resident and does not need airconditioning is inevitably heated. The local air conditioner, however,does not heat the area that does not need air conditioning, and thus,energy can be saved by use of the local air conditioner. In addition,when the indoor unit stops, a load applied to the compressor can bereduced. That is, driving of the compressor with a high load can beavoided, thereby increasing the efficiency of the heat pump cycle. Fromthe foregoing findings, the inventors of the present disclosure arrivedat the aspects below.

The first aspect of the present disclosure is superior to the techniquesdescribed in Japanese Unexamined Patent Application Publication No.2011-7356 and Japanese Patent No. 4958448 in the following points. InJapanese Unexamined Patent Application Publication No. 2011-7356 andJapanese Patent No. 4958448, the power generator 120 is used as a motor.However, since the power generator 120 is originally provided in orderto generate electric power, the power generator 120 cannot generate asufficient degree of driving force when being used as a motor. Althoughthe power generator 120 can be used as a motor so as to drive thecompressor 112 in the case of a low load, the use of the power generator120 alone is not sufficient for driving the compressor 112 in the caseof a high load, because the compressor 112 needs to be driven at aconsiderably high speed. Thus, the techniques described in JapaneseUnexamined Patent Application Publication No. 2011-7356 and JapanesePatent No. 4958448 cannot increase the efficiency under high loads.

On the other hand, the gas heat pump air conditioning system of thepresent disclosure includes the power generator driven by the gas engineand the local air conditioner that air conditions the interior space byusing electric power generated by the power generator. Thus, the use ofthe local air conditioner in an air-conditioned area with a high loadcan reduce the load of the compressor constituting the heat pump cycle.As a result, the efficiency of the gas heat pump air conditioning systemin the case of a high load can be increased.

In a second aspect, the control circuit of the gas heat pump airconditioning system of the first aspect, for example, may stop the powergenerator while air conditioning by the heat exchanger is beingperformed, and supply electric power from the power generator to thelocal air conditioner while air conditioning by the heat exchanger isstopped. In the second aspect, a load applied to the heat pump cycle canbe reduced, and the efficiency of the heat pump cycle in the case of ahigh load can be increased.

In a third aspect, the control circuit of the gas heat pump airconditioning system of the first or second aspect, for example, mayswitch an operation mode between a first operation mode in which theinterior space is air-conditioned by the heat exchanger and a secondoperation mode in which the interior space is air-conditioned by thelocal air conditioner, in accordance with the air conditioning load ofthe interior space. In the third aspect, a load applied to the heat pumpcycle can be reduced, and the efficiency of the heat pump cycle in thecase of a high load can be increased.

In a fourth aspect, the control circuit of the gas heat pump airconditioning system of the first or second aspect may control the powergenerator and the heat exchanger such that the interior space isair-conditioned by the local air conditioner in a case where a gas flowrate necessary for the gas engine in air-conditioning the interior spaceby the heat exchanger is higher than a gas flow rate necessary for thegas engine in air-conditioning the interior space by the local airconditioner, and the interior space is air-conditioned by the heatexchanger in a case where a gas flow rate necessary for the gas enginein air-conditioning the interior space by the heat exchanger is lowerthan or equal to the gas flow rate necessary for the gas engine inair-conditioning the interior space by the local air conditioner. In thefourth aspect, it is possible to ensure saving of gas while maintainingcomfort.

In a fifth aspect, the control circuit of the gas heat pump airconditioning system of the first aspect, for example, may cause thepower generator to supply electric power to the local air conditionerand starts air conditioning performed by the local air conditioner whena temperature change amount per unit time in the interior space that hasbeen air-conditioned by the heat exchanger is less than or equal to apredetermined value.

In a sixth aspect, the control circuit of the gas heat pump airconditioning system of the fifth aspect, for example, may select a firstoperation mode in which the interior space is air-conditioned by theheat exchanger in a case where the temperature change amount per unittime in the interior space that has been air-conditioned by the heatexchanger exceeds the predetermined value, and selects a secondoperation mode in which the interior space is air-conditioned by thelocal air conditioner in a case where the temperature change amount perunit time in the interior space that has been air-conditioned by theheat exchanger is less than or equal to the predetermined value.

In a seventh aspect, the heat exchanger included in the gas heat pumpair conditioning system of one of the first to sixth aspects, forexample, may include a plurality of heat exchangers, and the controlcircuit may cause the local air conditioner to air-condition theinterior space, instead of at least one of the plurality of heatexchangers. In the seventh aspect, on/off of the heat pump cycle can beavoided as much as possible. This also contributes to an increase in theefficiency of the air conditioning system.

In an eighth aspect, the gas heat pump air conditioning system of one ofthe first to seventh aspects, for example, may further include a clutchthat transmits power from the gas engine to the power generator, and thecontrol circuit may control the number of revolutions of the powergenerator by controlling the clutch. In the eighth aspect, a sufficientamount of electric power can be generated by the power generator, andthus, energy (gas) is not easily wasted.

In a ninth aspect, the heat exchanger included in the heat pump cycle ofthe gas heat pump air conditioning system of one of the first to eighthaspects, for example, may include a plurality of heat exchangers, theplurality of heat exchangers may include a first heat exchanger and asecond heat exchanger, the air-conditioned area included in the interiorspace may include a plurality of air-conditioned areas, and theplurality of air-conditioned areas may include anordinary-air-conditioned area that is air-conditioned by the first heatexchanger and a locally-air-conditioned area that is air-conditioned byone of the second heat exchanger and the local air conditioner. When airconditioning is performed in manners appropriate for the individualair-conditioned areas, the efficiency of the air conditioning system canbe easily increased.

A gas heat pump air conditioning system according to a tenth aspectincludes: a gas engine that drives a compressor by using gas as a fuel;a heat pump cycle including the compressor and a heat exchanger disposedin an interior space and air-conditioning the interior space by the heatexchanger; a power generator that is driven by the gas engine andgenerates electric power; and a local air conditioner thatair-conditions the interior space by using the electric power generatedby the power generator, in which an air-conditioned area with a highdegree of the air conditioning load is air-conditioned by the local airconditioner, and the other air-conditioned areas are air-conditioned bythe heat exchanger.

In the tenth aspect, the same advantages as those of the first aspectcan be obtained. In addition, in the tenth aspect, the number of indoorunits can be reduced, and no complicated control is required. Thus, aninitial investment cost can be reduced.

In an eleventh aspect, the heat pump cycle of the gas heat pump airconditioning system of the tenth aspect, for example, may perform aheating operation on the interior space by the heat exchanger, the localair conditioner may perform a heating operation on the interior space,the heat exchanger may be disposed on a ceiling of the interior space,and the local air conditioner may be disposed on a floor of the interiorspace.

In a twelfth aspect, the local air conditioner of the heat pump cycle ofthe gas heat pump air conditioning system of one of the first to tenthaspects may be a portable electric warm-air fan heater. If the heat pumpcycle is portable, the local air conditioner can be easily disposed neara resident.

Embodiments of the present disclosure will be described with referenceto the drawings. The present disclosure is not limited to theembodiments below. In this description, the term “air conditioning”includes both cooling and heating.

First Embodiment

As illustrated in FIG. 1, a gas heat pump air conditioning system 100according to a first embodiment includes an outdoor unit 10, a firstindoor unit 15 a disposed in an interior space and serving as a heatexchanger, a second indoor unit 15 b disposed in the interior space andserving as a heat exchanger, a control circuit 50, and a local airconditioner 80. The outdoor unit 10 includes a compressor 12, a heatexchanger 13, and an expansion valve 14. The compressor 12, the heatexchanger 13, the expansion valve 14, the first indoor unit 15 a, andthe second indoor unit 15 b are connected to form a loop by refrigerantpipes 16, thereby forming a heat pump cycle 17.

The outdoor unit 10 further includes a gas engine 11, a powertransmission mechanism 40, a clutch 33, a power transmission mechanism41, a power generator 20, and an inverter 21. The power transmissionmechanism 40 includes a pulley 30, a pulley 31, and a belt 32. The powertransmission mechanism 41 includes a pulley 34, a pulley 35, and a belt36. The power transmission mechanisms 40 and 41 are not limited to belttransmission mechanisms, and may be other transmission mechanisms suchas chain transmission mechanisms and gear transmission mechanisms. Thecompressor 12 is driven by the gas engine 11 through the powertransmission mechanism 40. The clutch 33 transmits power from the gasengine 11 to the power generator 20. The power generator 20 is driven bythe gas engine 11 through the clutch 33 and the power transmissionmechanism 41. A torque that is transmitted from the gas engine 11 to thepower generator 20 can be adjusted by controlling the clutch 33.

The power generator 20 is connected to the local air conditioner 80through the inverter 21 and the panel board 22. The local airconditioner 80 is operated by electric power generated by the powergenerator 20.

The control circuit 50 includes a load detector 51, a switchingdeterminer 52, a constant setting unit 53, a clutch controller 54, andan indoor unit controller 55. The load detector 51 detects intendedtemperatures that have been individually set for air-conditioned areasin the interior space, and calculates air conditioning loads of theair-conditioned areas. The constant setting unit 53 stores a constantindicating characteristics of the heat pump cycle 17 and a constant thataffects the air conditioning loads of the air-conditioned areas. Theseconstants are used for calculating the air conditioning loads. Based onthe calculation results of the air conditioning loads of theair-conditioned areas, the switching determiner 52 determines whetherlocal air conditioning using the local air conditioner 80 is necessaryor not. The indoor unit controller 55 transmits an ON signal or an OFFsignal to the indoor unit 15 b in response to the determination of theswitching determiner 52. In response to the determination of theswitching determiner 52, the clutch controller 54 calculates a necessarynumber of revolutions of the power generator 20, and transmits a controlsignal to the clutch 33.

The control circuit 50 only needs to have a control function andincludes a processing unit (nor shown) and a memory unit (not shown)storing a control program. Examples of the processing unit include anMPU and a CPU. Examples of the memory unit include a memory. The controlcircuit may be a single control circuit that performs centralizedcontrol or may be constituted by a plurality of control circuits thatperform decentralized control in cooperation (the same holds for controlcircuits of other embodiments and variations thereof). The memory unitstores a program for appropriately operating the air conditioning system100. Functions of the load detector 51, the switching determiner 52, theconstant setting unit 53, the clutch controller 54, and the indoor unitcontroller 55 can be achieved by software executed on a hardware. Thecontrol circuit 50 may be disposed in the outdoor unit 10. In a mannersimilar to a building energy management system (BEMS), the controlcircuit 50 may be provided in a central monitoring unit that enablescontrol of units of the air conditioning system 100 through networks.

As illustrated in FIG. 1, suppose a plurality of air-conditioned areas60, 61, and 62 are present in the same room. In this embodiment, theair-conditioned areas 60, 61, and 62 include an ordinary-air-conditionedarea 60, a locally-air-conditioned area 61, and an air-conditioning-freearea 62. The ordinary-air-conditioned area 60 is an air-conditioned areawith an ordinary load. The locally-air-conditioned area 61 is anair-conditioned area with a high air conditioning load. Theair-conditioning-free area 62 is an area where no residents are presentand air conditioning is not required. A first indoor unit 15 a isdisposed above the ordinary-air-conditioned area 60, and a second indoorunit 15 b is disposed above the locally-air-conditioned area 61. A localair conditioner 80 is also disposed in the locally-air-conditioned area61. The ordinary-air-conditioned area 60 is air-conditioned by the firstindoor unit 15 a. The locally-air-conditioned area 61 is air-conditionedby one of the second indoor unit 15 a and the local air conditioner 80.Air conditioning suitable for each of the air-conditioned areasfacilitates an increase in the efficiency of the air conditioning system100.

Suppose a generally heavily clothed resident 70 usually works in theair-conditioned area 60. Suppose a generally lightly clothed resident 71usually works in the locally-air-conditioned area 61. In the case ofheating, the locally-air-conditioned area 61 is an air-conditioned areawith a high load in view of a comfort index PMV. Heating energynecessary for the ordinary-air-conditioned area 60 is supplied from thefirst indoor unit 15 a, and heating energy necessary for thelocally-air-conditioned area 61 is supplied from the second indoor unit15 b.

The local air conditioner 80 is disposed in the locally-air-conditionedarea 61. The local air conditioner 80 is supplied with electric powergenerated by the power generator 20 through a power line 24. In thismanner, the locally-air-conditioned area 61 is locally supplied withheating energy or cooling energy. The locally-air-conditioned area 61can be supplied with heating energy or cooling energy from each of theheat pump cycle 17 and the local air conditioner 80. Examples of thelocal air conditioner 80 include an electric warm-air fan heater and afan cooler. The local air conditioner 80 is preferably equipment that isportable with human power. If the local air conditioner 80 is portable,the local air conditioner 80 can be easily disposed near the resident.

The control circuit 50 obtains an intended temperature TL (a targettemperature) of the first indoor unit 15 a, an intended temperature TH(a target temperature) of the second indoor unit 15 b, and an outdoorair temperature To. Based on the intended temperature TL, the intendedtemperature TH, and the outdoor air temperature To, the control circuit50 determines whether the local air conditioner 80 effectivelyair-conditions the locally-air-conditioned area 61. In other words, thecontrol circuit 50 determines whether the local air conditioner 80should perform local air conditioning or not. The control circuit 50issues an instruction of turning the second indoor unit 15 b on or off,to the second indoor unit 15 b. The control circuit 50 outputs a clutchlevel U to the clutch 33. The control circuit 50 adjusts the amount ofpower generation Pg of the power generator 20.

Operation of the air conditioning system 100 will now be described.

The load detector 51 of the control circuit 50 calculates a load of theair-conditioned area that is air-conditioned by the first indoor unit 15a and a load of the air-conditioned area that is air-conditioned by thesecond indoor unit 15 b, and transmits calculation results to theswitching determiner 52. One of techniques for calculating loads is atechnique of calculating loads Q (W) from an intended temperature T (K)of an indoor unit and the outdoor air temperature To. A intendedtemperature T can be input by the resident to a remote controller of theindoor unit. The control circuit 50, for example, directly obtains anintended temperature T of the indoor unit through wireless communicationfrom the remote controller of the indoor unit. The outdoor airtemperature To can be obtained from, for example, an outdoor airtemperature sensor (not shown). The load Q can be calculated fromExpression (1):

Q=(T−To)·k·A   (1)

where A (m²) is a space surface area of a space to be air-conditionedand k (W/(m²·K)) is an overall heat transmission coefficient withrespect to the space surface area.

The load detector 51 calculates an air conditioning load QL fromExpression (2-1):

QL=(TL−To)·kL·AL   (2-1)

where QL is an air conditioning load of the ordinary-air-conditionedarea 60, TL is an intended temperature, AL is a space surface area, andkL is an overall heat transmission coefficient. Similarly, the loaddetector 51 calculates an air conditioning load QH from Expression(2-2):

QH=(TH−To)·kH·AH   (2-2)

where QH is an air conditioning load of the locally-air-conditioned area61, TH is an intended temperature, AH is a space surface area, and kH isan overall heat transmission coefficient.

The space surface areas AL and AH and the overall heat transmissioncoefficients kL and kH are individually designed values of the airconditioning system 100. Thus, these values are previously stored in theconstant setting unit 53, obtained from the constant setting unit 53 bythe load detector 51 when necessary, and used for the calculations ofExpressions (2-1) and (2-2).

Next, the switching determiner 52 of the control circuit 50 obtains aload Q from the load detector 51 and calculates a gas volume Vhp(m³/min) necessary for driving the compressor 12 of the heat pump cycle17. The gas volume Vhp can be calculated by using a coefficient ofperformance (COP) ((min·W)/m³) indicating the efficiency of the heatpump cycle 17, from Expression (3):

Vhp=Q/COP   (3)

Referring to FIG. 3, efficiency characteristics of the gas heat pumpcycle will be described. FIG. 3 shows a relationship between theefficiency (COP) of the heat pump cycle and the load Q. For example, theefficiency with respect to the air conditioning load QL in theordinary-air-conditioned area 60 is COP_L. This relationship isdetermined on the basis of performance of equipment such as thecompressor 12 and the configuration of the heat pump cycle 17. Ingeneral, in the gas heat pump cycle, the efficiency is at maximum with aload called an intermediate load. The efficiency is low with a ratedload higher than the intermediate load and a higher load. The efficiencyis also low in a region of a low load or a load called a partial load.Although Japanese Unexamined Patent Application Publication No.2011-7356 and Japanese Patent No. 4958448 described above showtechniques of increasing the efficiency under a low load or a partialbad, but fail to disclose techniques of increasing the efficiency undera high bad.

In consideration of the relationship between the efficiency COP and thebad Q, a gas volume Vhp_ALL necessary for air conditioning by the firstindoor unit 15 a and the second indoor unit 15 b is calculated. The areathat is air-conditioned by the first indoor unit 15 a is theordinary-air-conditioned area 60, and the air conditioning load thereofis QL. The area that is air-conditioned by the second indoor unit 15 bis the locally-air-conditioned area 61 and the air-conditioned-free area62. The air-conditioning-free area 62 does not directly affect warmth orcoldness felt by the resident 71. However, since the second indoor unit15 b is disposed on the ceiling, air-conditioning is inevitably needed.Suppose the bad of the air-conditioning-free area 62 is QLoss, the airconditioning bad of the second indoor unit 15 b is QH+QLoss. The sum ofthe air conditioning loads of the first indoor unit 15 a and the secondindoor unit 15 b is QL+QH+QLoss. As shown in FIG. 3, if the efficiencywith respect to QL+QH+QLoss is COP_ALL, gas volume Vhp_ALL can becalculated, by using Expressions (2-1), (2-2), and (3), from Expression(4):

$\begin{matrix}{{Vhp\_ ALL} = {{( {{QL} + {QH} + {QLoss}} )\text{/}{COP\_ ALL}} = {( {{( {{TL} - {To}} ) \cdot {kL} \cdot {AL}} + {( {{TH} - {To}} ) \cdot {kH} \cdot {AH}} + {QLoss}} )\text{/}{COP\_ ALL}}}} & (4)\end{matrix}$

In this manner, the gas volume Vhp_ALL necessary for covering all theair conditioning loads by the first indoor unit 15 a and the secondindoor unit 15 b can be calculated from the loads QL and QH calculatedby the load detector 51. In other words, the gas volume Vhp_ALLnecessary for covering the air conditioning loads only by the heat pumpcycle 17 without using the local air conditioner 80 can be calculated.

Then, a gas volume Vg necessary for the gas engine 11 in a case wherethe local air conditioner 80 is operated with electric power Pg(W)generated by the power generator 20 is calculated.

FIG. 4 is a graph showing a relationship between a clutch level in theclutch 33 and the number of revolutions of the power generator 20.Suppose the clutch level that is an input of the clutch 33 is U(dimensionless) and the number of revolutions of the power generator isN (rpm), the relationship expressed by Expression (5) below isestablished:

N=α1·U   (5)

where α1 (rpm) is a constant. The clutch level U is an input signal tothe clutch 33. As the clutch level U is increased, a driving forcetransmitted from the gas engine 11 to the power generator 20 increases,and the number of revolutions N of the power generator 20 increases. Thenumber of revolutions Nmax is the number of revolutions of the gasengine 11 obtained when the clutch 33 operates to cause power of the gasengine 11 to be transmitted to the power generator 20, and varies inaccordance with the number of revolutions necessary for the compressor12.

FIG. 5 is a graph showing a relationship between the number ofrevolutions of the power generator 20 and the gas volume consumed by thegas engine 11. Suppose the gas volume consumed by the gas engine 11 isVg and the number of revolutions of the power generator is N, therelationship of Expression (6) is established:

Vg=α2·N   (6)

where α2 (m³/(min·rpm)) is a constant.

FIG. 6 is a graph showing a relationship between the number ofrevolutions and the amount of power generation of the power generator20. Suppose the amount of power generated by the power generator 20 isPg and the number of revolutions of the power generator 20 is N, therelationship of Expression (7) is established:

Pg=α3·N   (7)

where α3 (W/rpm) is a constant.

From Expressions (5) to (7), the relationship between the amount ofpower generation Pg of the power generator 20 and the necessary gasvolume Vg is expressed as Expression (8):

Vg=(α2/α3)·Pg   (8)

In a case where the load Q is covered by operating the local airconditioner 80, the relationship between the necessary electric powerand the load Q is expressed as Expression (9):

Q=β·(Pg+Pin)   (9)

where Pin is the amount of power purchased from the commercial powersupply 23, Pg is the amount of power generated by the power generator20, and β (dimensionless) is the efficiency of the local air conditioner80.

The amount of power generation Pg of the power generator 20 is generallysufficient for providing the load Q. In this case, since the amount ofpower purchase Pin from the commercial power supply 23 is zero, therelationship between the amount of power generation Pg and the load Q isexpressed as Expression (10):

Q=β·Pg   (10)

In a case where the load QH is covered by the local air conditioner 80,instead of the second indoor unit 15 b, by air-conditioning thelocally-air-conditioned area 61, a gas volume Vg_H necessary for the gasengine 11 can be calculated, by using Expressions (8) and (10), fromExpression (11):

$\begin{matrix}{{Vg\_ H} = {{( {{\alpha 2}\text{/}{\alpha 3}} ) \cdot {Pg}} = {{( {{\alpha 2}\text{/}{\alpha 3}} ) \cdot ( {{QH}\text{/}\beta} )} = {( {{\alpha 2}\text{/}{\alpha 3}} ) \cdot ( {{( {{TH} - {To}} ) \cdot {kH} \cdot {AH}}\text{/}\beta} )}}}} & (11)\end{matrix}$

In a case where the locally-air-conditioned area 61 is air-conditionedby the local air conditioner 80, the second indoor unit 15 b is stopped.On the other hand, the ordinary-air-conditioned area 60 isair-conditioned by the first indoor unit 15 a. As described withreference to FIG. 3, the efficiency with respect to the load QL iscorrelated with the COP_L. Thus, the gas volume Vhp_L necessary forcovering the load QL with the first indoor unit 15 a can be calculated,by using Expressions (3) and (4), from Expression (12):

$\begin{matrix}{{Vhp\_ L} = {{{QL}\text{/}{COP\_ L}} = {{( {{TL} - {To}} ) \cdot {kL} \cdot {AL}}\text{/}{COP\_ L}}}} & (12)\end{matrix}$

The gas volume necessary in a case where the local air conditioner 80 isnot used and air conditioning is performed only by the first indoor unit15 a and the second indoor unit 15 b is Vhp_ALL. The gas volumenecessary in a case where the locally-air-conditioned area 61 isair-conditioned by the local air conditioner 80 and theordinary-air-conditioned area 60 is air-conditioned by the first indoorunit 15 a is (Vg_H+Vhp_L).

The use of the local air conditioner 80 is effective for saving energyin a case where the gas volume (Vg_H+Vhp_L.) is smaller than the gasvolume Vhp_ALL. Thus, if Expression (13):

Vg _(—) H+Vhp _(—) L<Vhp _(—) ALL   (13)

is established, the locally-air-conditioned area 61 is air-conditionedby the local air conditioner 80. On the other hand, if Expression (13)is not established, the locally-air-conditioned area 61 isair-conditioned by the second indoor unit 15 b.

The switching determiner 52 of the control circuit 50 determines whetherExpression (13) is established or not. If Expression (13) isestablished, a signal is transmitted from the switching determiner 52 tothe indoor unit controller 55, and a stop signal is transmitted as anindoor unit instruction from the indoor unit controller 55 to the secondindoor unit 15 b. At the same time, a signal is transmitted from theswitching determiner 52 to the clutch controller 54, and a clutch levelU is transmitted from the clutch controller 54 to the clutch 33. Theclutch level U_H necessary for the power generator 20 to generate anelectric power Pg necessary for the local air conditioner 80 can becalculated, by using Expressions (2), (5), (6), and (11), fromExpression (14):

$\begin{matrix}{{U\_ H} = {{{N\_ H}\text{/}\text{α1}} = {{{Vg\_ H}\text{/}( {{\alpha 1} \cdot {\alpha 2}} )} = {{( {1\text{/}( {{\alpha 1} \cdot {\alpha 3} \cdot \beta} )} ) \cdot {QH}} = {( {1\text{/}( {{\alpha 1} \cdot {\alpha 3} \cdot \beta} )} ) \cdot ( {{TH} - {To}} ) \cdot {kH} \cdot {AH}}}}}} & (14)\end{matrix}$

where N_H is the number of revolutions necessary for the power generator20 to generate electric power Pg.

The clutch controller 54 transmits to the clutch 33 the clutch level U_Hcalculated from Expression (14). The clutch 33 can transmit power of thegas engine 11 to the power generator 20 through the power transmissionmechanism 41. As a result, minimum electric power necessary for thelocal air conditioner 80 to cover the load Q_H of thelocally-air-conditioned area 61 can be generated by the power generator20.

If Expression (13) is not established, it is determined that the use ofthe local air conditioner 80 is not effective. Thus, no signal istransmitted to the indoor unit controller 55, and the second indoor unit15 b does not stop and continues to operate. No signal is transmittedfrom the switching determiner 52 to the clutch controller 54, either,and the clutch level U is not transmitted to the clutch 33. The powergenerator 20 does not generate power for the local air conditioner 80.

In this manner, the control circuit 50 controls the number ofrevolutions of the power generator 20 and on/off operation of the secondindoor unit 15 b such that when the indoor unit 15 b operates, the powergenerator 20 stops, and when the second indoor unit 15 b stops, thepower generator 20 operates and supplies electric power to the local airconditioner 80. In other words, the control circuit 50 switches, inaccordance with the degree of the air conditioning load of the interiorspace, between the operation mode in which the interior space (thelocally-air-conditioned area 61) is air-conditioned by the second indoorunit 15 b and the operation mode in which the interior space (thelocally-air-conditioned area 61) is air-conditioned by the local airconditioner 80. In this manner, the load applied to the heat pump cycle17 can be reduced, thereby increasing the efficiency under a high loadon the heat pump cycle 17.

More specifically, the control circuit 50 controls the power generator20 and the second indoor unit 15 b such that the locally-air-conditionedarea 61 is air-conditioned by the local air conditioner 80 in a casewhere the gas flow rate necessary for the gas engine 11 inair-conditioning the locally-air-conditioned area 61 by the secondindoor unit 15 b is higher than the gas flow rate necessary for the gasengine 11 in air-conditioning the locally-air-conditioned area 61 by thelocal air conditioner 80. The control circuit 50 also controls the powergenerator 20 and the second indoor unit 15 b such that thelocally-air-conditioned area 61 is air-conditioned by the second indoorunit 15 b in a case where the gas flow rate necessary for the gas engine11 in air-conditioning the locally-air-conditioned area 61 by the secondindoor unit 15 b is lower than or equal to the gas flow rate necessaryfor the gas engine 11 in air-conditioning the locally-air-conditionedarea 61 by the local air conditioner 80. Then, it is possible to ensuresaving of gas while maintaining comfort.

In this embodiment, the interior space (the locally-air-conditioned area61) is air-conditioned by the local air conditioner 80 instead of atleast one indoor unit 15 b selected from the indoor units 15 a and 15 b.The other indoor unit 15 a is operated to air-condition the interiorspace (the ordinary-air-conditioned area 60) independently of on/off ofthe local air conditioner 80. In this manner, on/off of the heat pumpcycle 17 can be avoided as much as possible. This also contributes to anincrease in efficiency of the air conditioning system 100.

In air-conditioning the locally-air-conditioned area 61 by the local airconditioner 80, the control circuit 50 outputs an appropriate clutchlevel U. Then, an appropriate torque is transmitted to the powergenerator 20. That is, the control circuit 50 controls the number ofrevolutions of the power generator 20 by controlling the clutch 33.Accordingly, a sufficient amount of electric power is generated by thepower generator 20, and thus, energy (gas) is less likely to be wasted.

The load QLoss of the air-conditioning-free area 62, the efficiencyCOP_ALL corresponding to the air conditioning load (QL+QH+QLoss), andthe efficiency COP_L with respect to the air conditioning load QL aredesign values in the air conditioning system 100. Thus, these values arestored in the constant setting unit 53, obtained from the constantsetting unit 53 by the switching determiner 52 when necessary, and usedfor calculations in Expressions (4) and (14). The constant α1 indicatingcharacteristics of the clutch 33, the constant α2 indicating therelationship between the power generator 20 and the gas engine 11, theconstant α3 indicating characteristics of the power generator 20, andthe efficiency β of the local air conditioner 80 are also design valuesin the air conditioning system 100. Thus, these values are stored in theconstant setting unit 53 and used by the switching determiner 52 and theclutch controller 54 when necessary.

In this embodiment, the locally-air-conditioned area 61 with a high loadis air-conditioned by the local air conditioner 80 with electric powergenerated by the power generator 20. Thus, a load applied to the heatpump cycle 17 can be reduced, and the efficiency of the heat pump cycle17 in a case of a high load can be increased. In addition, in a periodin which the air-conditioning-free area 62 is not air-conditioned,energy is not wasted. As a result, energy (gas) consumption can be savedin total. Thus, it is possible to provide the gas heat pump airconditioning system 100 having high efficiency under a high load as wellas a low load.

The control circuit 50 determines whether the local air conditioner 80should perform air conditioning while determining the loads of theair-conditioned areas (the ordinary-air-conditioned area 60 and thelocally-air-conditioned area 61). If the efficiency of the heat pumpcycle 17 is high, the main unit of air conditioning is not switched fromthe second indoor unit 15 b to the local air conditioner 80, and all thearea can be air-conditioned by the heat pump cycle 17 (the indoor units15 a and 15 b).

Since the local air conditioner 80 can be operated with electric powergenerated by the power generator 20, the degree of freedom ininstallation is high. For example, since the local air conditioner 80can be disposed near the resident 71, comfort of the resident can bemaintained.

Second Embodiment

As illustrated in FIG. 2, in a gas heat pump air conditioning system 200according to a second embodiment, the second indoor unit 15 b isomitted. That is, the air conditioning system 200 is configured suchthat an air-conditioned area (a locally-air-conditioned area 61) with ahigh air conditioning load is air-conditioned by a local air conditioner80, and the other air-conditioned area (an ordinary-air-conditionedarea) is air-conditioned by the indoor unit 15 a.

This embodiment is based on a premise that inequality of Expression (13)described in the first embodiment is always established. WhenExpressions (4), (11), and (12) are substituted into Expression (13),the following Expression (15) is derived:

(α2/α3)·((TH−To)·kH·AH/β)+(TL−To)·kL·AL/COP _(—)L<((TL−To)·kL·AL+(TH−To)·kH·AH+QLoss)/COP_ALL   (15)

In Expression (15), if the load QLoss of an air-conditioning-free area62 is significantly high, inequality of Expression (15) is alwaysestablished irrespective of an intended temperature TL, an intendedtemperature TH, and an outdoor air temperature To. As shown in FIG. 3,inequality of Expression (15) is also always established in a case wherethe efficiency with a high load is very low, that is, the COP_ALL ismuch smaller than the COP_L.

In this case, it is effective that the locally-air-conditioned area 61is always air-conditioned by the local air conditioner 80. Thus, thesecond indoor unit 15 b can be omitted. A clutch 33 always transmits themaximum driving force of a gas engine 11 to a power generator 20. Allthe electric power generated by the power generator 20 is supplied tothe local air conditioner 80 through a power line 24. Thus, the controlcircuit 50 of the first embodiment can also be omitted. In thisembodiment, the second indoor unit 15 b and the control circuit 50 canbe omitted. In other words, the number of indoor units can be reduced,and complicated control is not required. Thus, an initial investmentcost can be reduced.

In a case where only electric power generated by the power generator 20is insufficient as electric power required for the local air conditioner80, electric power can be supplied from the commercial power supply 23through the panel board 22. On the contrary, in a case where electricpower generated by the power generator 20 is in excess, the excesselectric power can be supplied to, and used in, other indoor electricalappliance (not shown) through the power line 24. This holds for thefirst embodiment.

Other Embodiments

The number of air-conditioned areas is not limited to two (e.g., theordinary-air-conditioned area 60 and the locally-air-conditioned area61). Even in a case where a larger number of air-conditioned areas arepresent, the number of indoor units and the number of local airconditioners 80 can be increased. The control circuit 50 may detect(obtain) comfort indexes PMV in the air-conditioned areas, instead of orin addition to the intended temperature TL, the intended temperature TH,and the outdoor air temperatures To.

The control circuit 50 may start air conditioning by the local airconditioner 80 by causing the power generator 20 to supply electricpower to the local air conditioner 80 when a temperature change amountTa per unit time in an interior space that is air-conditioned by a heatexchanger is less than or equal to a predetermined value C1.

Specifically, as illustrated in FIG. 7, the control circuit 50 maycontrol the power generator 20 and the local air conditioner 80, forexample. First, the control circuit 50 obtains the temperature changeamount Ta per unit time in an interior space (step S1). The controlcircuit 50 obtains a temperature detected by a temperature sensordisposed in the interior space and obtains the temperature change amountTa based on the temperature. For example, the control circuit 50 canobtain a temperature change amount Ta by obtaining from the temperaturesensor a room temperature T1 at a predetermined time and a roomtemperature T2 when a predetermined time Δt has elapsed from thepredetermined time and calculating |T1−T2|/Δt. Then, the control circuit50 determines whether the temperature change amount Ta per unit time inthe interior space is less than or equal to a predetermined value C1(step S2). If the temperature change amount Ta per unit time in theinterior space is less than or equal to the predetermined value C1, (Yesstep S2), the control circuit 50 causes the power generator 20 to supplyelectric power to the local air conditioner 80 and starts airconditioning by the local air conditioner 80 (step S3). On the otherhand, if the temperature change amount Ta per unit time in the interiorspace is larger than the predetermined value C1 (No in step S2), thecontrol circuit 50 performs step S1 again.

The control circuit 50 may select an operation mode based on therelationship between the temperature change amount Ta per unit time inthe interior space that is air-conditioned by a heat exchanger and apredetermined value C2. For example, when the temperature change amountTa per unit time in the interior space that is air-conditioned by theheat exchanger exceeds the predetermined value C2, the control circuit50 selects a first operation mode in which the interior space isair-conditioned by the heat exchanger. On the other hand, the controlcircuit 50 selects a second operation mode in which the interior spaceis air-conditioned by the local air conditioner 80 when the temperaturechange amount Ta per unit time in the interior space that isair-conditioned by the heat exchanger is less than or equal to thepredetermined value C2.

Specifically, as illustrated in FIG. 8, the control circuit 50 maycontrol the power generator 20, the local air conditioner 80, and theheat exchanger. First, the control circuit 50 obtains a temperaturechange amount Ta per unit time in an interior space (step S11), anddetermines whether the temperature change amount Ta per unit time in theinterior space exceeds the predetermined value C2 or not (step S12). Ifthe temperature change amount Ta per unit time in the interior spaceexceeds the predetermined value C2 (Yes in step S12), the controlcircuit 50 selects the first operation mode in which the interior spaceis air-conditioned by the heat exchanger (step S13). On the other hand,if the temperature change amount Ta per unit time in the interior spacedoes not exceed the predetermined value C2 (No in step S12), the controlcircuit 50 selects the second operation mode in which the interior spaceis air-conditioned by the local air conditioner 80 (step S14).

The technique described in this disclosure can provide an airconditioning system that can achieve both comfort of a resident and ahigh efficiency.

What is claimed is:
 1. A gas heat pump air conditioning systemcomprising: a gas engine; a heat pump cycle that includes a compressorand at least one heat exchanger, the compressor being driven by the gasengine, the at least one heat exchanger being disposed in an interiorspace and air-conditioning the interior space; a power generator that isdriven by the gas engine and that generates electric power; a local airconditioner that is disposed in the interior space and thatair-conditions the interior space by using the electric power generatedby the power generator; and a control circuit that controls the powergenerator and the heat exchanger in accordance with an air conditioningload of the interior space.
 2. The gas heat pump air conditioning systemof claim 1, wherein the control circuit stops the power generator whileair conditioning by the heat exchanger is being performed, and supplieselectric power from the power generator to the local air conditionerwhile air conditioning by the heat exchanger is stopped.
 3. The gas heatpump air conditioning system of claim 1, wherein the control circuitswitches an operation mode between a first operation mode in which theinterior space is air-conditioned by the heat exchanger and a secondoperation mode in which the interior space is air-conditioned by thelocal air conditioner, in accordance with the air conditioning load ofthe interior space.
 4. The gas heat pump air conditioning system ofclaim 1, wherein in a case where a gas flow rate necessary for the gasengine in air-conditioning the interior space by the heat exchanger ishigher than a gas flow rate necessary for the gas engine inair-conditioning the interior space by the local air conditioner, thecontrol circuit controls the power generator and the heat exchanger,thereby causing the interior space to be air-conditioned by the localair conditioner, and in a case where a gas flow rate necessary for thegas engine in air-conditioning the interior space by the heat exchangeris lower than or equal to the gas flow rate necessary for the gas enginein air-conditioning the interior space by the local air conditioner, thecontrol circuit controls the power generator and the heat exchanger,thereby causing the interior space to be air-conditioned by the heatexchanger.
 5. The gas heat pump air conditioning system of claim 1,wherein the control circuit causes the power generator to supplyelectric power to the local air conditioner and starts air conditioningperformed by the local air conditioner when a temperature change amountper unit time in the interior space that has been air-conditioned by theheat exchanger is less than or equal to a predetermined value.
 6. Thegas heat pump air conditioning system of claim 5, wherein the controlcircuit selects a first operation mode in which the interior space isair-conditioned by the heat exchanger in a case where the temperaturechange amount per unit time in the interior space that has beenair-conditioned by the heat exchanger exceeds the predetermined value,and selects a second operation mode in which the interior space isair-conditioned by the local air conditioner in a case where thetemperature change amount per unit time in the interior space that hasbeen air-conditioned by the heat exchanger is less than or equal to thepredetermined value.
 7. The gas heat pump air conditioning system ofclaim 1, wherein the heat exchanger included in the heat pump cycleincludes a plurality of heat exchangers, and the control circuit causesthe local air conditioner to air-condition the interior space, insteadof at least one of the plurality of heat exchangers.
 8. The gas heatpump air conditioning system of claim 1, further comprising a clutchthat transmits power from the gas engine to the power generator, whereinthe control circuit controls the number of revolutions of the powergenerator by controlling the clutch.
 9. The gas heat pump airconditioning system of claim 1, wherein the heat exchanger included inthe heat pump cycle includes a plurality of heat exchangers, theplurality of heat exchangers include a first heat exchanger and a secondheat exchanger, the air-conditioned area included in the interior spaceincludes a plurality of air-conditioned areas, and the plurality ofair-conditioned areas include an ordinary-air-conditioned area that isair-conditioned by the first heat exchanger and alocally-air-conditioned area that is air-conditioned by one of thesecond heat exchanger and the local air conditioner.
 10. A gas heat pumpaft conditioning system comprising: a gas engine; a heat pump cycle thatincludes a compressor and a heat exchanger, the heat exchanger beingdisposed in an interior space and air-conditioning the interior space; apower generator that is driven by the gas engine and that generateselectric power; and a local air conditioner that air-conditions theinterior space by using the electric power generated by the powergenerator, wherein an air-conditioned area with a high degree of the airconditioning load is air-conditioned by the local air conditioner, andthe other air-conditioned areas are air-conditioned by the heatexchanger.
 11. The gas heat pump air conditioning system of claim 10,wherein the heat pump cycle performs a heating operation on the interiorspace by the heat exchanger disposed on a ceiling of the interior space,and the local air conditioner is disposed on a floor of the interiorspace and performs a heating operation on the interior space.
 12. Thegas heat pump air conditioning system of claim 1, wherein the local airconditioner is a portable electric warm-air fan heater.